DE2932571A1 - METHOD FOR PRODUCING SPHERICAL CARBON PARTICLES OR SPHERICAL CARBON PARTICLES - Google Patents

Description

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description

The invention relates to a process for the production of spherical carbon particles or spherical activated carbon particles from pitch or a heavy oil, in particular with a low softening point of less than 150 ^° C.

So far, spherical carbon particles or spherical particles of activated carbon on the basis of pitch using a pitch were prepared, the (usually above 150 ⁰ C) has a higher softening point than the oxidation starting temperature, wherein the pitch material is formed into spherical particles, the particles are oxidized to the infusibilization and then the spherical particles are carbonized or activated.

Pitch with a softening point of more than 150 ^° C. is, however, a very special type and is usually not available on an industrial scale, so that the use of such a pitch causes considerable costs compared to the use of a conventional pitch used for technical purposes. It is therefore uneconomical to produce spherical carbon particles or spherical activated carbon particles from such a pitch.

The softening point of pitch available for technical purposes is of the order of 40 to 80 ^° C., while that of a heavy oil is usually not higher than 150 ^° C., with heavy oil being understood as the remainder that is obtained during the refining of petroleum, for example Asphalt, tar and high boiling point oils. Easily accessible pitch or heavy oil therefore has a softening point that is too low to be used directly as a

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material for the production of spherical carbon particles or spherical activated carbon particles.

Coal-type pitch is also difficult to use as a base material for activated carbon because it is spherical Coal particles tend to crack due to the great tendency of such pitch to form spheres tend, furthermore, the generated coal is difficult to activate.

The invention has set itself the task of solving these problems and creating a method that can be used in the Is able to advantageously use spherical carbon particles or spherical activated carbon particles from commercially available coal pitch or petroleum pitch with a low softening point.

This object is achieved by the method according to the invention.

When carrying out the method according to the invention first a mixture with an optimal softening point and viscosity for the shaping of the spherical particles produced by adding and mixing in a material capable of modifying the viscosity, as well as a material capable of increasing the softening point to a commercially available coal pitch or petroleum pitch with a low softening point, such as "soft pitch", "medium pitch" or "high pitch" or a heavy oil, such as natural asphalt, petroleum asphalt or a solvent-extracted Asphalt, whereupon the particles obtained in this way become spherical particles of coal or spherical activated carbon particles are processed.

It should be noted that when the mixture is processed into the spherical products, voids

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can be formed inside the processed products, so that these products are mechanically fragile. In view of this fact, one embodiment looks according to the invention, the addition of a material capable of preventing the formation of such voids prior to manufacture the mixture.

The material used to increase the softening point of the coal or petroleum pitch or heavy oil of the present invention Invention used can be made from a mononitroaromatic compound such as nitrobenzene, nitrotoluene or nitrophenol, polynitroaromatic compound, the dinitrobenzene, dinitrotoluene, dinitrophenol or tetranitromethane, Quinones, such as benzoquinone, naphthoquinone or toluquinone, or polycarboxylic acid anhydrides, such as maleic anhydride or pyromellitic anhydride. Of these materials are nitrobenzene and dinitrobenzene most preferred because they not only excellently increase the softening point of the pitch and heavy oil, but also effectively mesophase sphericity stop the bad luck.

One such material used for increasing the softening point of the pitch or heavy oil is used preferably in an amount of 0.2 to 20% by weight, based on the pitch or heavy oil with a low softening point, added. It should be noted that it does not achieve a satisfactory increase in the softening point when the amount of material added is below the range defined above. the Addition of the material in an excess of 20% by weight is inexpedient for economic reasons.

The softening point increasing effect of the above-mentioned material on the pitch or heavy oil is such as it is believed to be due to an oxidative polycondensation reaction that occurs when the material dem

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Pitch or sulfur is added and heated to a temperature of 150 to 350 ^{° C.}

The softening point of the pitch or heavy oil used according to the invention is not critical for economic reasons However, for reasons related to the material to be added, it is preferable that the softening point mentioned above higher than room temperature.

When carrying out the process according to the invention, a viscosity modifier is used to improve the Processability of the pitch or heavy oil when processing into spherical particles, the pitch or heavy oil added to the softening point increasing material. One such viscosity modifier is preferably an organic solvent that has good compatibility with pitch and heavy oil and one Has a boiling point of over 150 ° C. Examples of such organic solvents are the aromatic hydrocarbons, like durene, naphthalene, alky! naphthalenes and Biphenyl and chlorinated hydrocarbons such as trichlorobenzene or chloronaphthalene. Of these organic Naphthalene is most preferred because of its pronounced viscosity-modifying effect on solvents Pitch and heavy oil and also extracting in the extraction treatment for making the spherical products porous relieved.

Such a viscosity modifier is preferably in an amount of 5 to 50 wt .-%, based on the Pitch or heavy oil, added. An amount below the above-mentioned range cannot do the viscosity required for processing the pitch or heavy oil mixture into preferably spherical particles while a larger amount outside the range leads to an excessively high porosity.

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when the obtained spherical particles with a solvent are extracted, so that a poor mechanical strength of the product is the result.

The viscosity modifier can be the pitch or Heavy oil either at the same time as the material increasing the softening point or then added and concentrated after the softening point of the pitch or heavy oil has been increased accordingly.

In addition to the aforementioned softening point increasing material and viscosity modifier you can also add a material which acts to improve the texture of the spherical particles becomes compact, so that the likelihood of voids being formed inside the particles is suppressed. A such material can, for example, be a higher aliphatic hydrocarbon such as fluid paraffin solid paraffin or polyethylene, also an alicyclic hydrocarbon such as decalin or an alkylcyclohexane, a higher alcohol such as stearyl alcohol, lauryl alcohol or cetyl alcohol, or another material such as a silicone oil. The formation of voids inside of the spherical product causes decreased mechanical strength as mentioned above. That The aim of using the above-mentioned material is therefore to reduce the fragility of the product to prevent. In general, the softening point increasing materials tend to be generated easily of voids inside the spherical product. However, there is no need to do so Use material when there is no possibility that voids will be formed in the spherical product will.

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In this way a mixture is made by adding the softening point increasing material, the viscosity modifier and optionally a material capable of causing voids in the molded product to prevent it being made into a pitch or heavy oil with a low softening point, whereupon this mixture is shaped into spheres.

Several methods are available for processing the mixture into spherical particles. For example, you can (1) Stir a melt of the mixture at high speed in hot water which is a suspending agent contains so that the mixture is distributed in the water phase, forming spheres; (2) you can get a melt spray from the mixture into a gaseous phase from a nozzle. In addition, there is (3) the possibility pulverize the solidified mass of this mixture and place it in a disk-type or drum-type pelletizer at high temperature to deform the mixture into balls. These methods have in common that the mixture is deformed into spherical particles while they are in the molten state, whereupon solidification by cooling takes place. Of these methods, the method (1) in which the melt the mixture is distributed in water and shaped into a spherical shape, most suitable for obtaining essentially real spherical particles.

Then the above-mentioned viscosity modifier, contained in the spherical particles obtained, substantially completely below Using an extracting agent that contains hardly any pitch or heavy oil, the main component of the product, extracted. During the extraction of the viscosity modifier from the particles by this extraction treatment, the particles become porous.

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The porous structure of the spherical particles, which is achieved by the extraction treatment, contributes to an increase in the softening point of the particles to a value which is higher than the oxidation starting temperature (usually above 150 ^° C.), and also to the uniform distribution of the oxidizing agent within the structure of the particles at the infusibilization step.

The extractant used in the extraction treatment can be a lower aliphatic hydrocarbon, such as hexane, heptane, cyclohexane, naphtha or kerosene, or a lower aliphatic alcohol such as methanol or ethanol, be. To carry out the extraction of the spherical particles using the extractant can any conventional method can be used.

The obtained during the extraction treatment, porous spherical particles are then rendered infusible by oxidation with an oxidizing agent at a temperature below 400 ^0C. This infusibilization of the porous spherical particles using an oxidizing agent increases the softening point of the pitch or heavy oil by polycondensation, whereby the volatile components of the pitch or heavy oil are rendered non-volatilizable by polycondensing such components to increase the carbonization rate.

The oxidizing agent used for infusibilizing the porous spherical particles can be any conventional one Oxidizing agents used wisely, such as oxygen, ozone, sulfur trioxide gas (SO ·,), Nitrogen dioxide, chlorine or air. It is also possible to use an oxidative liquid such as sulfuric acid, Phosphoric acid, nitric acid, chromic acid solution, a permanganic acid solution, a peroxide solution or a

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Solution of hypochlorous acid. Of these oxidizing agents, ozone, sulfur trioxide gas, nitrogen dioxide and chlorine can be used in the form of a mixed gas that is diluted with air or nitrogen. Furthermore, these oxidizing agents can be used either alone or in combination. The infusiblization treatment is carried out at a temperature which is lower than the softening point is of the porous product and below 400 ⁰ C, as mentioned above. In carrying out this treatment in practice, the softening point of the porous spherical particles rises with the progress of the infusibilization treatment, so it is appropriate to gradually increase the remeltability treatment temperature in accordance with the increase in the softening point, since in this way a noticeable reduction in the length of time required for treatment is possible.

The infusible, porous spherical particles are then fired in an inert atmosphere at a temperature above 600 ^° C., during which they are carbonized to obtain spherical carbon particles. Spherical activated carbon particles can also be easily obtained by either directly activating the infusibilized spherical particles or activating the spherical carbon particles with an activator composed mainly of oxygen or water vapor.

As mentioned above, it is possible according to the invention to advantageously obtain a porous spherical product with a low degree of mesophase sphericity from a technically available coal pitch or petroleum pitch with a relatively low softening point and a heavy oil. Such materials have hitherto been used in their present form as material for manufac-

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Position of spherical carbon particles or spherical activated carbon particles unsuitable.

The porous spherical particles of coal produced by carbonizing of the porous spherical particles are obtained are particularly suitable as carbon-containing fillers for specific uses. Spherical activated carbon particles, which are created by activating the spheres that are too small shaped spherical particles or by activating spherical carbon particles obtained by carbonization of the coal particles produced are of excellent quality and performance.

The following examples illustrate some embodiments of the invention without limiting it.

example 1

Samples (samples No. 1 to 4) of the coal pitch, petroleum pitch and natural asphalt given in Table I below with the softening points also shown in the table are mixed with a material that has their softening point able to increase, also a material which is able to modify its viscosity, and a material capable of preventing voids from being formed in the spherically shaped product. The added ones Quantities are also shown in Table I. Each of the mixtures produced in this way is used in deformed into porous spheres in the following manner.

100 g of each mixture are in an autoclave having a capacity of 500 1, which is provided with agitating blades was charged and heated to 260 ⁰ C with stirring over a period of 1 hour to effect an increase in the softening point of the sample. After this

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As an action to increase the softening point, the contents of the autoclave are ^{cooled to 150 °} C., whereupon 350 kg of an O ₇ 3% aqueous solution of saponified polyvinyl acetate (degree of saponification: 88%) are added. Then, at a high speed is stirred at the same temperature over a period of 20 minutes (280 ÜPM), to distribute the mixture in the water phase, followed by cooling to 40 ⁰ C. A slurry of a ball mass is obtained. The spherical pitch or asphalt mass obtained is filtered, dewatered and then in an approximately 10-fold amount. stirred on n-hexane for a period of 1 hour to extract the viscosity modifier from the mass. After the above-described measure has been repeated twice, the mass is air-dried to obtain porous spheres. The softening points of the porous ball preforms thus obtained are also shown in Table I (the porous pitch and asphalt preforms obtained in the above-described manner are hereinafter referred to as R-1, R-2, R-3 and R-3, respectively. R-4 designated).

Table I.

Sample no.

Source material

Type

Softening point batch

Coal pitch coal pitch
48 ⁰ C 72 ° C
71 kg 66 kg

Petroleum pitch 8O ⁰ C 72 kg

Natural asphalt 120 ⁰ C 62 kg

by means of an increase
of softening
point Type
Batch m-dinitro
benzene
3 kg Benzoquinone
8 kg m-dinitro
benzene
2 kg Maleic acid
anhydride
8 kg O
Jl)
O
O
O
-3 Additive viscosity modes
fixing agent Type
Batch naphthalene
25 kg Methy! Naphtha
lin
25 kg naphthalene
25 kg Duren
30 kg Ό929 Means of Ver
hindrance of
Blanks Type fixed pa
subtle
1 kg Polyethylene
1 kg Stearyl alcohol
get
1 kg none Porous balls out
Bad luck and asphalt Softening
Point
Mark 205 ⁰ C
R-1 19O ⁰ C
R-2 215 ⁰ C
R-3 -185 ⁰ C
R-4

Note: The softening point is measured using a flow tester determines CO (Test sample: 1 g, 10 kg / cm ^a; rate of temperature rise: 6 ^e C / min). ^ j ₁

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A portion of each of the porous spherical preforms R-2 to R-4 is fired by heating from room temperature to 1000 ⁰ C at a heating rate of 250 ° C / h in a nitrogen atmosphere to obtain spherical carbon particles. The properties of the spherical carbon products obtained are shown in Table II.

Tabel - II R-3 - R-4 - Bullet - Bullet Mark R-2 no no shape Bullet <10 <10 Surface cracks no track low Spherulite (vol-%) < 10 Blanks track 0.48 0.45 average - Grain size (im) 0.52 - Surface area (m ² / g) * 1 ■ Xj-absorption ^Δ (mg / g) * 2

Note: * 1: Measured by nitrogen adsorption

the B.E.T.-method.

* 2: Adsorption per 1 g of activated carbon at an equilibrium density of 1 g / l, obtained from the isothermal adsorption lines.

A portion of the porous spherical preforms R- 1 to R-4 is at 900 ⁰ C at a heating rate of 250 ° C / h heated in a nitrogen gas stream using a fluidized bed. After switching to steam , the preforms are placed in a steam stream for a period of 2 hours to effect steam activation and to generate active

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coal held. The properties of the activated carbon products obtained in this way are as follows Table III.

Table III

R-I R-2 R-3 R-4 Mark Bullet Bullet Bullet Bullet- shape shaped shaped shaped föntdg no no no no Surface cracks <10 <10 <10 <10 Spherulite (vol-%) track track track low Blanks average 0.48 0.50 0.47 0.42 Grain size (ram) 1000 1100 1200 960 Surface area (m ² / g) * 1 960 1010 1050 950 iXj adsorption
(mg / g) * 2

Comment:

* 1: Measured by nitrogen adsorption after the B.E.T.-method.

* 2: Adsorption per 1 g of activated carbon in one
Equilibrium density of 1 g / l, obtained from the isothermal adsorption lines ,

Example 2

Samples 5 to 8 of coal pitch and solvent-extracted asphalt given in Table IV with the
The softening points given there are mixed with a material which is capable of increasing the softening point, in the amounts given in the table. Each of the mixtures prepared in this way is placed in an autoclave (the same as in Example 1), whereupon the contents of the autoclave

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240 ° C with stirring for a period of 5 hours is heated to carry out the treatment to increase the softening point. Treated in this way Pitch and asphalt samples have the softening points given in Table IV.

Table IV

Prcbe no.

Type to increase Batch money money Money- with solution of enlargement bad luck bad luck bad luck medium ex Starting
iriaterial Expansion
chungs point of interest Expansion 80 ⁰ C 80 ⁰ C 80 ⁰ C trailed
asphalt
nnop Point tes chungs DU V- * Batch Treated Point 98 kg 96 kg 94 kg 90 kg material Type Bad luck and symbol m-dinitro m-dinitro m-dinitro Benzo- asphalt benzene benzene benzene chinone 2 kg 4 kg 6 kg 10 kg 150 ⁰ C 175 ° C 205 ⁰ C 160 ⁰ C P-5 P-6 P-7 P-8

A portion of the pitch and asphalt samples treated in this way (with an increased softening point) is taken as a sample and mixed with a material that is able to modify the viscosity, as well as mixed with a material, which is able to prevent the formation of voids in the preforms. The amounts added are in the Table V summarized below.

Each of the mixtures prepared in this way is introduced into an autoclave (cf. as in the previous examples). It is at 160 ⁰ C for a time

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Stirred span of 1 hour in order to melt and mix the materials, whereupon a distribution in the water phase at 150 ⁰ C according to the method described in Example 1 takes place. The obtained dispersed particles are extracted in the same manner as in Example 1 to obtain porous balls made of the pitch and asphalt (the porous spherical preforms made of pitch and asphalt are hereinafter referred to as R-9, R-10, R -11 or R-12).

Table V

Sample no. symbol
Batch 9 10 11 12th Treated
Bad luck and
asphalt P-5
.74 kg P-6
74 kg P-7
75 kg P-8
69 kg

Viscosity ^, - type naphtha 1 kg naphtha methyl Duren modification lin lin naphtha funds 181 ° C lin Batch
O) 25 kg 25 kg 25 kg 30 kg '.μ material for type Polyethy R-9 solid none Polyethy • η prevention len paraffin len 1 kg - 1 kg Porous balls made of expansion Bad luck and asphalt 210 ⁰ C 225 ° C 195 ° C Point symbol R-10 R-11 R-12

A part of the porous spherical pitch and asphalt preforms R-9 to R-12 thus obtained becomes the same carbonization and activation treatments as in Example 1 for the recovery of spherical coal particles and activated carbon particles. These coal products have the properties summarized in Tables VI and VII.

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Table VI

(Properties of spherical coal particles) symbol R-9 R-10 R-10 R-11 R-12 I. R-12 symbol shape Bullet
shaped Bullet
shaped Bullet
shaped Bullet
shaped Bullet
shaped Bullet
shaped shape Surface cracks no no no no no no Surface cracks Blanks track track track low track track Blanks Sphkrulit (vol .-%) OO <10 <10 <10 OO <10 Spherulite (vol .-%) average
Particle size (ran) 0.49 0.52 0.50 0.55 0.47 0.44 average
Particle size (mti) Surface (m ^a / g) - - 1200 - - 970 Surface area (m ² / g) •! "- Adsorption (mg / g) - - 1100 - - 890 ^ Adsorption (mg / g) Table VII of spherical Activated carbon) (Properties R-9 R-11 Bullet
shaped Bullet
shaped no no track low OO <10 0.47 0.52 1000 1100 920 1000

Example 3

Both 72 kg of a Äthylenbodenöls, and 45 kg of coal pitch having a softening point of 74 ⁰ C with 4 kg of
or 5 kg of nitrobenzenes mixed. The mixtures obtained are placed in 500 liter autoclaves equipped with stirring paddles.

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are seen, filled, and ^{heated to 240 0} C with stirring for a period of 5 hours. The ÄthylenbodenÖlmischung thus obtained has a softening point of 164 ° C. and the coal pitch mixture obtained an increased softening point of 150 ⁰ C.

30 g of the ethylene soil oil mixture are mixed with 16 kg of naphthalene and 0.3 kg of polyethylene, while 30 g of the Coal pitch mixture are mixed with 16.2 kg of naphthalene and 0.45 kg of solid paraffin.

Each of the mixtures obtained is filled into the autoclave described above and ^{heated to 160 °} C. with stirring to melt.

After the fusion treatment 120 kg of a 0.3% aqueous solution of saponified polyvinyl acetate (degree of saponification: 88%) are respectively charged in the autoclave, is followed by stirring with a speed of 280 rpm at 150 ⁰ C for a period of 20 minutes to to disperse the respective mixtures in the water phase.

Each of the spherical ethylene soil oil and coal pitch masses obtained in this way is treated with η-hexane after Method for obtaining porous spheres described in Example 1 extracted.

The thus obtained porous spheres at 900 ⁰ C with a Erhitzungsgeschwxndigkeit of 250 ° C / h heated in a nitrogen gas stream using a fluidized bed. After switching to a water vapor flow, the porous spheres are held in the water vapor flow for a period of 2 hours in order to bring about activation by water vapor in order to obtain activated carbon particles.

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The characteristic properties of the obtained activated carbon particles are shown in Table VIII.

Table VIII Coal pitch spherical no symbol <10 shape Starting material track Surface cracks Ethylene floor oil Spherulite (vol .-%) spherical 0.80 Blanks no 1200 average Ό0 1140 Grain size (mm) track Surface area (m ² / g) J ₂ adsorption (mg / g) 0.80 Example 4 1150 1130

72 parts by weight of coal pitch with a softening point of 43 ° C., 8 parts by weight of m-dinitrobenzene (agent for increasing the softening point) and 20 parts by weight of naphthalene (viscosity modifier) are mixed. The mixture is filled into an autoclave and stirred therein at 260 ⁰ C for a period of 3 hours, in order to increase the softening point of coal pitch. An extrusion then takes place from a nozzle with a diameter of 0.4 mm at a temperature of 180 ^° C., the extrudate being dropped by gravitational force in η-hexane into a cylinder with a diameter of 2 m and a length of 5 m. In this way, balls with a size of approximately 0.9 mm are obtained. These balls are extracted with hexane to obtain η-spherical porous bodies having a softening point of 205 ⁰ C.

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These porous bodies are treated in a similar manner as described in Example 1, whereby essentially spherical activated carbon particles with a spherulite content of less than 10%, an average particle size of 0.81 mm, a surface area of 1000 m ² / g and a J ₂ - Adsorption of 980 mg / g can be obtained.

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Claims (5)

Claims Process for the production of spherical carbon particles or spherical activated carbon particles by Mixing a pitch or heavy oil with a material that can modify its viscosity, Melting and shaping the mixture into spherical particles, extracting the spherical ones Particles with a solvent that is practically incapable of dissolving the pitch or heavy oil. 030007/0929 S MÜHCHEN 88-SIEBERTSTR. 4-POSTRACH 880720 · CABLE: MITEBOPAT ■ TEl ·. (089) 47400S-TELEX 5-242S5 2332571 dissolve, but the material capable of modifying the viscosity is able to dissolve, the material being removed from the particles to obtain porous spherical particles, subjecting the obtained porous spherical particles to a treatment for rendering infusible in an oxidizing environment, and then Carbonization of the particles or further activation of the carbonized particles, characterized in that a pitch or heavy oil with a low softening point below 150 ⁰ C is used as the starting material, at least one material selected from the group consisting of mononitroaromatic compounds, polynitroaromatic compounds, quinones and Polycarboxylic anhydrides, is mixed with the pitch or heavy oil and the mixture obtained ^{is heated to a temperature between 150 and 350 0} C to increase the softening point of the pitch or the heavy oil before melting and shaping. 2. The method according to claim 1, characterized in that the material to increase the softening point of the Pitch or heavy oil in an amount of 0.2 to 20 wt .-%, based on the pitch or heavy oil, used will. 3. The method according to claim 1 or 2, characterized in that that the material used consists of mononitrobenzene. 4. The method according to claim 1 or 2, characterized in that the material used consists of dinitrobenzene. 5. Process for the production of spherical carbon particles or spherical activated carbon particles by 030007/0929 mixing a pitch or heavy oil with a material capable of modifying its viscosity. Melting and shaping the mixture into spherical particles, extracting the spherical particles with a solvent which is practically incapable of dissolving the pitch or heavy oil, but is capable of dissolving the material which is able to modify the viscosity, the material being made from the Particles is removed to obtain porous spherical particles, subjecting the obtained porous spherical particles to a treatment for rendering infusible in an oxidizing environment and then carbonizing the particles or further activating the carbonized particles, characterized in that a pitch or heavy oil with a low softening point below 150 ⁰ C is used as the starting material, at least one material selected from the group consisting of mononitroaromatic compounds, polynitroaromatic compounds, quinones and polycarboxylic anhydrides, and one material selected from the group consisting of flui the paraffin, solid paraffin, polyethylene, alicyclic hydrocarbons, alkylcyclohexane, higher alcohols and silicone, are mixed with the pitch or heavy oil, whereupon the resulting mixture to a temperature of 150 to 350 ⁰ C to increase the softening point of the pitch or heavy oil before Melting and deforming is heated. 030007/0929